As I said, there are no published refereces, but I have another example. The closest discussions on this are in Mees and James.

Imagine 2 films with the same speed. One uses flat t-grains and another uses octahedral grains. Now, lets assume that they both are coated at the same speed.

The t-grain allows light through the grain like mica. The octahedral grain acts like a diamond. You cannot see through it, and you get lots of surface reflections.

So, grains lower down in the t-grain emulsion coating still see light, but the tubidity and reflectivity in the octahedral emulsion limit the penetration of light and sharpness of the coating. The coated quantity of silver at the same speed might be different.

Coating more silver in the t-grain case won't help much as you started at the max, and coating more of the octahedral grain can cause a speed loss.

If we compare a 10 micron 1% iodide crystal with a 5 micron 10% iodide crystal, the silver levels might be the same and the speeds might be the same, but grain would be less with the 5 micron crystal all else being equal. So there is a very wide window of design parameters that must be considered.

This type of engineering consequence is similar to asking how big beams should be in a bridge, and how many cables should be used. There are tradeoffs only apparent to engineers. I would not try to design a bridge and your teacher should not try to design a film unless he has actually done it in practice.

If you have a problem, put him on APUG and have him PM me. BTW, what school is this???? It sure does not sound like RIT.

It's a film school, the teacher isn't really an engineer and doesn't have any sort of degree really, he is just used to be a professional cinematographer. He is probably alright in an artistic sense, but when it comes to technical details, well...

Agfa used to provide the silver content of all their colour films & papers in their sales literature, this was actually for silver recovery reasons, I did have data for Kodak films, but it will be in the UK.

The Kodak data was in one of their silver recovery publications available on the net, it compared the average throughput of minilabs - different types of film & silver content, it used actual examples of Kodak Films and the 400 ISO contained more silver than the 100 ISO. It wasn't a huge amount more but it was significant, so in one way your teacher is right the answer is "true"

That is why I said "It Depends". This question is so fraught with engineering and design considerations that you might be comparing a T-grain with a K-grain film in your example, and Kodak had no desire to clarify the matter for obvious reasons.

Another thing is that different generations of a given product may vary. I've seen color paper vary by 500 mg / square meter between two minor variations due to a coupler change. But the results to the customer were unchanged. The photofinisher saw a difference in silver recovery rate.

This is not a yes, no answer.

Thanks Ian for the additional input. The ISO 400 film might have 300 mg/square foot and the ISO 100 might be 200 mg / square foot, but we would have to know the crystal habit and iodide content as well to make a valid judgement. (sorry for the mixed units but that is what I used at EK and I'm not going to convert what I 'know'.)